We tested a 518d in 'Luxury' specification, a mid-grade trim, with the optional paddle-shifted eight-speed torque convertor automatic and variable damper control – all of which would set you back £35,735.
This, it appears, is a particularly fine combination to opt for. Firstly, you get the slick-shifting, easy-going ZF eight-speed automatic, the wide ranging ratios of which make good use of the diesel's output.
Secondly, besides vast amounts of kit, this trim level equips the 5-series with 18-inch alloy wheels and tyres with a substantial amount of sidewall. Consequently the 5-series rides in a pliant, cosseting fashion that befits its executive saloon nature.
Lastly, and wrapping up the package neatly, the addition of the variable damper control gives the 5-series a wider-ranging breadth of talent than the standard 5-series. A new Comfort+ mode delivers a smoother ride than was possible previously, or, if desired, a Sport mode offers improved responses, minimised body roll and better comfort in high-speed cornering situations.
Is the 518d's engine capable of summing up the kind of performance and refinement that a luxury saloon necessitates though? Well, almost. The 0-62mph sprint is dispatched in a sensible 9.4sec, and in-gear acceleration proves swift enough to not be an annoyance. Above 1500rpm the diesel pulls with comparative vigour, up until around 3500rpm, after which its performance tails off.
Fortunately, despite the narrow 2000rpm spread of power, the sheer number of gear ratios on offer means progress is always swift and the diesel is always kept turning within its favoured range of crank speed. This is beneficial for both the engine and the driver, as worked hard the diesel engine is predictably noisy after 3000rpm – or at full throttle – but the rapid gear changes usually keep it below that speed.
Driven in a sensible fashion, however, or once up to cruising speeds, the engine is quiet and – unlike the BMW X3 – there's no persistent light diesel clatter in the background. The only oddity is that the ZF gearbox is very keen to get into higher gears, for efficiency reasons, which can lead to the engine being laboured somewhat. Once the revs drop below 1500rpm an audible low-frequency drone fills the cabin and a light vibration can be felt; drop down a gear – from seventh to sixth at 30mph, for example – and smoothness and silence is instantly restored.
The engine is otherwise refined, barring its full-throttle, rev-counter roaming vocality – although the swift-acting stop-start system does serve to intermittently remind you that it's definitely a diesel, with the momentary silence and then eruption of noise highlighting how much quieter a petrol would be.
Predictably the BMW also appears to struggle to meet its claimed economy figures. BMW states an average of 64.2mpg but during testing our example averaged 40mpg, after a mix of driving. Adopting a pedestrian, unswerving gait on the motorway may permit you to achieve headier heights but, if you're considering a 518d, we'd suggest you take 40mpg as the baseline and anything above will be a bonus. Either way this means you'll revel in a potential range of upwards of 600 miles.
All in all, the 518d is a reassuringly competent – and quietly satisfying – car to drive, particularly in the specification tested. It corners with aplomb, with plenty of front-end grip and well weighted, precise steering, and there's plenty of traction and stopping power on offer. Its high standards of body control and smooth ride make even fast cross-country driving both comfortable and rewarding, too. It's one of those cars that proves adept in pretty much any situation, a car that you'd be happy to see waiting for you in an airport car park at the end of a long day or at the start of a trek across some Welsh highlands.
Inside little has changed; it's still as comfortable, quiet and as well designed as ever. Admittedly the design of the interior isn't as cohesive or modern-looking as that of, say, the Audi A6, but it's still smartly styled – and there's plenty of room in the cabin and the boot alike.
Luxury trim models feature a lot of equipment as well, helping justify the nigh-on £35k list price – which may otherwise seem a lot for a four-cylinder diesel saloon. The standard SE model on which the Luxury is based features dual-zone climate, Bluetooth connectivity, a USB port, DAB, a 6.5-inch colour screen, Xenon headlights, leather trim, tyre pressure monitoring, automatic lights and wipers, parking sensors and an auto-dimming rear view mirror.
Opting for the Luxury specification, however, expands on this further with a 20GB hard disc drive-based media system, myriad upgraded trims and detail parts, the BMW Professional Media system with sat-nav, a sports multi-function steering wheel and voice control.